Compound semiconductor light emitting device and its manufacturing method

ABSTRACT

A compound semiconductor light emitting device for preparing a chip which improves the light extraction efficiency, enables mounting of easy positioning with only once wire bonding, and leads to a reduction in the manhour. One face of an insulative substrate ( 11 ) is overlaid with a semiconductor layer ( 4 ) consisting of a plurality of semiconductor thin films to form an active layer ( 15 ). One electrode ( 33 ) is formed on the top face of this semiconductor layer ( 4 ), and the other electrode ( 33 ) on the other face of the insulative substrate ( 11 ). For the exposure of a first semiconductor thin film layer ( 13 ) connected to the other electrode ( 33 ), the semiconductor film over the first semiconductor thin film layer ( 13 ) is removed to form an exposure region ( 10 ). This exposure region ( 10 ) is provided with a through hole ( 2 ) penetrating through the insulative substrate ( 11 ) and first semiconductor thin film layer ( 13 ).  
     The first semiconductor thin film layer ( 13 ) and the other electrode ( 33 ) are electrically connected with a conductive material ( 3 ) formed on the through hole ( 2 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a compound semiconductor light emittingdevice such as a blue light emitting diode and a blue laser diode aswell as its manufacturing method. This invention particularly relates toa light emitting device comprising a nitride-based compoundsemiconductor epitaxially grown on an insulative substrate such as asapphire substrate, and its manufacturing method.

2. Description of Prior Art

Epitaxial growth of nitride-based compound semiconductors used for bluelight emitting diodes, blue laser diodes and the like is generallyperformed on a sapphire (Al₂O₃) substrate whose lattice constant issimilar to that of the nitride-based compound semiconductors. FIG. 23illustrates an example of a basic structure of a blue light emittingsemiconductor device comprised of a nitride-based compoundsemiconductor. A buffer layer 220 made of Al_(x)Ga_(1-x)N (0≦X≦1) forexample is formed on a sapphire substrate 210, and an n-type contactlayer 230 made of n-type GaN doped with silicon (Si) for example isformed on the buffer layer 220. An n-type cladding layer 240 made ofn-type Al_(x)Ga_(1-x)N (0≦X≦1) doped with silicon (Si) for example isformed on the n-type contact layer 230. A multi-quantum well structureactive layer 250 having a composition of Al_(a)In_(b)Ga_(1-a-b)N (0≦a,0≦b, a+b≦1) for example is formed on the n-type cladding layer 240. Onthis active layer 250, a p-type cladding layer 260 made of p-typeAl_(y)Ga_(1-y)N (0≦Y≦1)doped with magnesium (Mg) for example is formed,and a p-type contact layer 270 made of p-type GaN doped with magnesium(Mg) is formed on the p-type cladding layer 260.

A p-type electrode 280 is provided on a surface of the p-type contactlayer 270. A part of the laminated semiconductor layer is etched toexpose the n-type contact layer 230, on which an n-type electrode 290 isprovided.

Electric current does not pass between the electrodes when theelectrodes are respectively provided on a rear surface of the substrateand a front surface of the semiconductor layer to bring a pair ofelectrodes like a conventional light emitting device comprising aconductive substrate because the sapphire substrate behaves as aninsulator.

Therefore, as described above, a part of the semiconductor layer isremoved from its front surface so that a semiconductor layer of oneconductivity type is exposed and an electrode of the other conductivitytype is formed on the remaining front surface. Thus, the nitride-basedcompound semiconductor light emitting device delivers performance byconducting electricity through a pair of electrodes, both of which areprovided on the front surface side of the semiconductor layer.

With this structure, the light extraction efficiency is low since thepair of electrodes existing on one side of the semiconductor deviceshade a lot of light. Also the pair of electrodes existing on one sideof the semiconductor device require wire-bonding at least twice. When achip is mounted face down on a board, the electrodes on the chip must beaccurately aligned with corresponding electrodes on the base, involvingdifficulty in precise alignment.

By the way a semiconductor light emitting device comprising a sapphiresubstrate with a contact hole to make contact with a semiconductor layerfrom the sapphire substrate side is disclosed in JP173235/1998, A. Thissemiconductor light emitting device comprises a sapphire substrate,wherein a rear side thereof is terraced, and a contact hole is providedto a thin-walled part of the terraced rear side of the substrate byreactive ion etching so as to make a semiconductor layer exposed.

It is surely possible to contact the semiconductor layer from thesapphire substrate side, and the electrodes are separately disposed onthe substrate side and the semiconductor layer side in the semiconductorlight emitting device disclosed in the above-mentioned specification.

However, the manufacturing process of this device becomes complicatedbecause the substrate must be terraced in advance to form the contacthole by reactive ion etching, which may cause frequent cracks in thesubstrate.

One of the objectives of the present invention is to improve the lightextraction efficiency. Another objective is to provide a chip whichenables mounting of easy positioning with only once wire bonding, andleads to a reduction in the manhour. A further objective of the presentinvention is to provide a device with reduced numbers of manufacturingprocesses and increased process yield by reducing occurrence of cracksin substrates.

SUMMARY OF THE INVENTION

The present invention is characterized by a compound semiconductor lightemitting device comprising an insulative substrate, a semiconductorlayer including a plurality of semiconductor thin films laminated on onesurface of the insulative substrate to form an active layer, oneelectrode provided on top surface of the semiconductor layer, the otherelectrode provided on the other surface of the insulative substrate, anexposure region formed by removing semiconductor films on a firstsemiconductor thin film layer so that the first semiconductor thin filmlayer to be connected to the other electrode is exposed, a through holeformed in the exposure region so as to penetrate the insulativesubstrate and the first semiconductor thin film layer, and an electricalpath formed in the through hole to electrically connect the firstsemiconductor thin film layer and the other electrode, as recited inclaim 1.

Also, the present invention is characterized by that the electrical pathis comprised of either a conductive material formed on a wall inside thethrough hole or a conductive material filled in the through hole, asrecited in claim 2.

Additionally, the present invention is characterized by that theelectrode for the electrical path provided on the other surface of theinsulative substrate comprises a pad electrode for wire bonding, asrecited in claim 3.

The present invention is further characterized by that the insulativesubstrate is a sapphire substrate, and the semiconductor thin film layeris a gallium nitride compound semiconductor layer, as recited in claim4.

Additionally, the present invention is characterized by that the oneelectrode is electrically connected to a base, and light is extractedmainly from the insulative substrate side, as recited in claim 5.

The present invention is also characterized by that a diameter of thethrough hole ranges from 30 μm to 100 μm, as recited in claim 6.

The present invention is characterized by that a groove or alongitudinal hole in addition to the through hole is formed in theinsulative substrate so that the electrode provided on the other surfaceof the insulative substrate and the first semiconductor thin film layerare electrically connected through an electrical path in addition to theelectrical path, as recited in claim 7.

The present invention is characterized by a manufacturing method of acompound semiconductor light emitting device comprising laminating aplurality of semiconductor thin films to form a semiconductor layer onone surface of an insulative substrate in order to form an active layer,and providing one electrode on top surface of the semiconductor layer,and the method further comprising forming an exposure region by removingsemiconductor films on a first semiconductor layer so that a firstsemiconductor thin film layer to be contacted with the other electrodeis exposed, forming a through hole in the exposure region so as topenetrate the insulative substrate and the first semiconductor layer bylaser-processing, and electrically connecting the electrode provided onthe other surface of the insulative substrate and the firstsemiconductor thin film layer through an electrical path formed in thethrough hole, as recited in claim 8.

Also, the present invention is characterized by that the through holepenetrating the device is formed in the exposure region by irradiating alaser from the laminated semiconductor layer side, as recited in claim9.

Additionally, the present invention is characterized by that an insideof the through hole is cleaned by dry etching after the through hole isformed, as recited in claim 10.

The present invention is further characterized by that an inside of thethrough hole is cleaned by dry etching using chloride or fluoride gasafter the through hole is formed, as recited in claim 11.

The present invention is characterized by that a wafer including aplurality of the light emitting devices is divided into individual lightemitting devices along grooves formed by laser-processing, as recited inclaim 12.

The present invention is characterized by that semiconductor layersdamaged by laser-processing are removed by dry etching using chloride orfluoride gas after the grooves are formed, as recited in claim 13.

The present invention is further characterized by that laser-processingfor forming the grooves is performed from the insulative substrate side,or from the laminated semiconductor layer side, or from both theinsulative substrate side and the laminated semiconductor layer side, asrecited in claim 14.

The present invention is characterized by a compound semiconductor lightemitting device comprising an insulative substrate, a semiconductorlayer including a plurality of semiconductor thin films laminated on onesurface of the insulative substrate to form an active layer, oneelectrode provided on top surface of the semiconductor layer, the otherelectrode provided on the other surface of the insulative substrate, alongitudinal hole formed by laser-processing, the hole penetrating theinsulative substrate and having a depth reaching a first semiconductorthin film layer to be connected to the other electrode, and anelectrical path made of a conductive material formed in the longitudinalhole to electrically connect the first semiconductor thin film layer andthe other electrode, as recited in claim 15.

Also, the present invention is characterized by that the conductivematerial is wholly or partially translucent, as recited in claim 16.

Additionally, the present invention is characterized by that thelongitudinal hole is covered with a pad electrode with a larger diameterthan a diameter of the longitudinal hole, as recited in claim 17.

The present invention is characterized by that the longitudinal hole isformed inside a lateral surface of the substrate at a constant distancefrom the lateral surface, as recited in claim 18.

The present invention is further characterized by that a pad electrodeis disposed apart from the longitudinal hole on the other surface of theinsulative substrate, and the pad electrode and the conductive materialare electrically connected, as recited in claim 19.

The present invention is additionally characterized by that a diameterof the longitudinal hole ranges from 30 μm to 100 μm, as recited inclaim 20.

The present invention is characterized by that a cross sectional shapeof the longitudinal hole is tapered toward a depth direction, as recitedin claim 21.

The present invention is further characterized by that the insulativesubstrate is a sapphire substrate, and the semiconductor thin film layeris a gallium nitride compound semiconductor layer, as recited in claim22.

The present invention is characterized by that light is extracted mainlyfrom the insulative substrate side, as recited in claim 23.

Additionally, the present invention is characterized by that a pluralityof the longitudinal holes are formed, and conductive materials disposedin the plurality of the longitudinal holes are interconnected on theother surface of the insulative substrate, as recited in claim 24.

The present invention is characterized by that the longitudinal hole isformed by irradiating a laser from the insulative substrate side, asrecited in claim 25.

Also, the present invention is characterized by that an inside of thelongitudinal hole is cleaned by dry etching using chloride or fluoridegas after the longitudinal hole is formed, as recited in claim 26.

The present invention is characterized by a manufacturing method of acompound semiconductor light emitting device comprising laminating aplurality of semiconductor thin films to form a semiconductor layer onone surface of an insulative substrate in order to form an active layer,and providing one electrode on top surface of the semiconductor layer,and the method further comprising forming a longitudinal hole bylaser-processing so as to have a depth reaching from the other surfaceof the insulative substrate to a first semiconductor thin film layer tobe connected to the other electrode, and electrically connecting theelectrode provided on the other surface of the insulative substrate andthe first semiconductor thin film layer through a conductive materialformed in the longitudinal hole, as recited in claim 27.

Also, the present invention is characterized by that a wafer including aplurality of the light emitting devices is divided into individual lightemitting devices along grooves formed by laser-processing, as recited inclaim 28.

The present invention is further characterized by that semiconductorlayers damaged by laser-processing are removed by dry etching usingchloride or fluoride gas after the grooves are formed, as recited inclaim 29.

And the present invention is characterized by that laser-processing forforming the grooves are performed from the insulative substrate side, orfrom the laminated semiconductor layer side, or from both the insulativesubstrate side and the laminated semiconductor layer side, as recited inclaim 30.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bottom plan view from a rear side of a compoundsemiconductor light emitting device 1 according to a first embodiment ofthe present invention. FIG. 2 is a cross sectional view of the compoundsemiconductor light emitting device 1 taken along the line II-II ofFIG. 1. FIG. 3 is a cross sectional view of an indicator including thecompound semiconductor light emitting device according to the firstembodiment of the present invention.

FIG. 4 is a bottom plan view from a rear side of the compoundsemiconductor light emitting device 1 according to a second embodimentof the present invention. FIG. 5 is a cross sectional view of thecompound semiconductor light emitting device 1 taken along the line V-Vof FIG. 4. FIG. 6 is a bottom plan view of a device according to amodified example of the second embodiment of the present invention. FIG.7 is a bottom plan view of a device according to another modifiedexample of the second embodiment of the present invention. FIG. 8 is across sectional view of an indicator including the compoundsemiconductor light emitting device according to the second embodimentof the present invention.

FIG. 9 is a bottom plan view from a rear side of the compoundsemiconductor light emitting device 1 according to a third embodiment ofthe present invention. FIG. 10 is a cross sectional view of the compoundsemiconductor light emitting device 1 taken along the line X-X of FIG.9.

FIG. 11 is a bottom plan view from a rear side of the compoundsemiconductor light emitting device 1 according to a fourth embodimentof the present invention. FIG. 12 is a cross sectional view of thecompound semiconductor light emitting device 1 taken along the line X-Xof FIG. 11.

FIG. 13 is a bottom plan view from a rear side of the compoundsemiconductor light emitting device 1 according to a fifth embodiment ofthe present invention. FIG. 14 is a cross sectional view of the compoundsemiconductor light emitting device 1 taken along the line X-X of FIG.13. FIG. 15 is a plan view of a device according to a modified exampleof the sixth embodiment of the present invention. FIG. 16 is a plan viewof a device according to another modified example of the sixthembodiment of the present invention.

FIG. 17 is a bottom plan view from a rear side of the compoundsemiconductor light emitting device 1 according to a seventh embodimentof the present invention. FIG. 18 is a cross sectional view of thecompound semiconductor light emitting device 1 taken along the line X-Xof FIG. 17.

FIG. 19 is a bottom plan view from a rear side of the compoundsemiconductor light emitting device 1 according to an eighth embodimentof the present invention. FIG. 20 is a cross sectional view of thecompound semiconductor light emitting device 1 taken along the line X-Xof FIG. 19. FIG. 21 is a cross sectional view of an indicator includingthe compound semiconductor light emitting device according to the eighthembodiment of the present invention. FIG. 22 is a bottom plan view of adevice according to a modified example of the eighth embodiment of thepresent invention.

FIG. 23 is a perspective view of a conventional device.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will be described in more details in conjunctionwith the accompanying drawings.

A first embodiment will be described by referring to FIGS. 1 and 2. FIG.1 is a bottom plan view of a compound semiconductor light emittingdevice 1 according to the first embodiment of the present invention asseen from the rear side. FIG. 2 is a cross sectional view of thecompound semiconductor light emitting device 1 taken along the lineII-II of FIG. 1.

The device 1 is characterized by comprising a hole 2 whichperpendicularly passes therethrough, as illustrated in FIG. 2. Thisthrough hole 2 is formed in a cylindrical or coned shape of 30 μm-100 μmin diameter by laser beams during laser-processing. The through hole 2may also be formed in an hourglass shape with diameters of openings inthe front and rear surfaces are wider than that in the middle.

In this embodiment, the hole 2 of 50 μm in diameter is formed bylaser-processing. It is preferable to irradiate the laser from thelaminated semiconductor layer side. The hole 2 is used as a pathconducting electricity in a perpendicular direction of the device (i.e.an electrical path). The electrical path is formed by filling inside thehole 2 with a conductive material 3. One example to provide thisconductive material 3 is to press conductive paste into the hole 2 tofill it up.

The conductive material 3 may also be formed by plating. For example,after evaporating and depositing nickel (Ni) as seed on the frontsurface of the hole 2, copper (Cu) is plated on the wall inside the hole2 to serve as the conductive material 3.

Additionally, molten solder or metallic micro-balls may also be usedinstead of conductive paste to fill up the hole 2.

The device 1 comprises a semiconductor layer 4 formed by laminating twoor more semiconductor thin films on a substrate 11. The substrate 11 isan insulative substrate. For example, the substrate 11 is a sapphiresubstrate. In the device 1, first conductivity type semiconductor layersand second conductivity type semiconductor layers are successivelyformed and laminated on a buffer layer 12 to form the semiconductorlayer 4. The buffer layer 12 is interposed between the substrate 11 andthe semiconductor layer 4.

The buffer layer 12 and the semiconductor layer 4 are formed by MOCVDmethod for example. An example of the buffer layer 12 is anAl_(x)Ga_(1-x)N (0≦X≦1) layer of 300 nm in thickness formed on thesubstrate 11. An n-type contact layer 13 made of an n-type GaN layer of3 μm in thickness doped with silicon (Si) for example is formed on thisbuffer layer 12. An n-type cladding layer 14 made of n-typeAl_(x)Ga_(1-x)N (0≦X≦1) of approximately 300 nm in thickness doped withsilicon (Si) for example is formed on the n-type contact layer 13. Amulti-quantum well structure active layer 15 having a composition ofAl_(a)In_(b)Ga_(1-a-b)N (0≦a, 0≦b, a+b≦1) is formed on the n-typecladding layer 14. A p-type cladding layer 16 made of p-typeAl_(y)Ga_(1-y)N (0≦Y≦1) of 300 nm in thickness doped with magnesium (Mg)for example is formed on the active layer 15. A p-type contact layer 17made of p-type GaN of 500 nm in thickness doped with magnesium (Mg) forexample is formed on the p-type cladding layer 16.

The semiconductor layer 4 may also be formed directly on the substrate11 without interposing the buffer layer 12.

A part of the n-type contact layer 13 (the first conductivity typesemiconductor layer) is exposed by removing the semiconductor layers(including the second conductivity type semiconductor layers) laminatedthereon and the exposed part of the contact layer 13 serves as anexposure region 10. The removal of the semiconductor layer 4 isperformed by a process including dry etching. The above-mentionedthrough hole 2 is provided in the exposure region 10.

To reduce damage to the semiconductor layer 4, it is preferable toirradiate a laser from the same side where the semiconductor layer 4 isformed. Although the hole 2 is set to be a cylindrical shape withidentical diameters from top to bottom, the completed hole 2 is slightlytapered. Alternately the through hole 2 may be formed by irradiating alaser from the substrate 11 side after irradiating the laser from thesemiconductor layer 4 side. A laser which emits light at a wavelength tobe absorbed in the substrate 1 1 is selected.

Since the substrate 11 is a sapphire substrate, a short-wavelength laserof 500 nm or shorter is used here. In this embodiment, an ultra violetlaser of wavelength 355 nm which is the third harmonic of a YAG lasercategorized as a solid-state laser is employed. The laser beam isirradiated from the semiconductor layer 4 side to a possible center ofthe hole 2, which will be the a center of an n-type electrode, for aboutone (1) second to form the hole 2 of 50 μm in diameter under thecondition; repetition frequency (f) 3 kHz, scanning rate 0.5 mm/second,defocus(DF)-80 μm and power 1.85 W. The diameter of the hole 2 may rangefrom 30 μm to 100 μm by controlling defocus(DF) and irradiating time.

A YAG laser's fundamental frequency of 1,060 nm, second harmonic of 533nm or fourth harmonic of 266 nm may also be employed.

The hole 2 formed in this way is filled up with the conductive material3. Prior to filling the hole 2 with the conductive material 3, parts ofthe semiconductor layer 4, which were damaged through the laser process,are removed by dry etching. Chloride or fluoride gas may be used asetching gas when removing the damaged parts of the semiconductor layerby dry etching.

The conductive material 3 may be filled as follows for example. First,the device is set upside down so that the semiconductor layer 4 isdirected downward, and a mask made of an adhesive sheet is applied tothe substrate 11. A portion is cut out from the mask in desired size sothat the conductive material is filled through the cutout portion. Aconductive material such as conductive paste is filled in centeringaround the cutout portion of the mask. Being compressed by a spatula andso on, the conductive material is press-fitted into the hole 2. Theadhesive sheet which is the mask is peeled off after the conductivematerial 3 is press-fitted into the hole 2 and the hole 2 is filled upwith the conductive material 3. The conductive material 3 is thenhardened by thermal treatment in a curing oven at a temperature of 200°C. for thirty minutes. After that, excess conductive material is removedby stripping solution, thereby completing the filling process of theconductive material 3 into the hole 2.

If necessary, the rear surface of the substrate 11 undergoes abacklapping process so that the thickness of the substrate 11 is reducedfrom 350 μm-430 μm to about 95 μm.

An electrode 31 to make ohmic contact is formed on the exposure region10 of the n-type contact layer 13. The n-type ohmic electrode 31 isdisposed on the exposure region 10 so as to make contact with the upperend of the through hole 2. The n-type ohmic electrode 31 formed on then-type contact layer 13 is electrically connected with the conductivematerial 3. If the conductive material 3 formed in the through hole 2can make ohmic contact with the n-type contact layer 13, the conductivematerial 3 disposed in the through hole 2 may also serve as theelectrode 31. In other words, the formation of the electrode 31 may beomitted by forming the conductive material 3 capable of making ohmiccontact with the n-type contact layer 13. The conductive material 3 inthe through hole 2 may serve as the electrode 31. A metallic materialused to form the electrode 31 may also be used for the conductivematerial 3 in the through hole 2.

An electrode 32 is formed on the p-type contact layer 17 to make ohmiccontact therewith. The electrode 32 is formed to cover the entiresurface of the p-type contact layer 17. The electrode 32 is a reflectiveelectrode to reflect light generated in the device 1.

The electrode 32 may be formed to cover only a part of the p-typecontact layer 17 to reflect some of the light generated in the device 1.The rest of the light, which was not reflected from this part, may bereflected from a member which is formed on the opposite side of thep-type contact layer 17 to the electrode 32, and which reflects thewavelength of the light generated in the device 1. When light is takenout from the electrode 32 side, the electrode 32 may be replaced with alight transmitting electrode through which light generated in the device1 can pass.

As illustrated in FIGS. 1 and 2, an electrode 33 is formed on theopposite surface (rear surface) of the substrate 11 to the surface wherethe semiconductor layer 4 is formed. The electrode 33 is electricallyconnected to the conductive material 3 disposed inside the through hole2. The conductive material inside the through hole 2 may also serve asthe electrode 33. The electrode 33 also serves as a pad electrode 34with a predetermined thickness. Although in this embodiment, the padelectrode 34 is disposed to cover the through hole 2 as shown in FIG. 1,the pad electrode 34 may also be disposed apart from the through hole 2.The pad electrode 34 is used for wire bonding. When the pad electrode 34and the exposure region 10 are viewed as if they are on a plane, theelectrode 34 and the exposure region 10 look overlapping one another.However, the pad electrode can be disposed so as not to overlap with theexposure region 10, for example, to a position as will be seen in FIG.19.

A plurality of devices 1 are formed on a substrate of about two inchesin diameter as a wafer (not shown). After that, the wafer is dividedinto dices to form individual devices. For dividing the wafer, the laserbeam used for the formation of the through hole 2 may also be employedto form grooves for division. Grooves for division may be formed on theopposite surface of the substrate 11 to the surface where thesemiconductor layer 4 is formed, or on the surface of the substrate 11where the semiconductor layer 4 is formed, or both the opposite surfaceof the substrate 11 to the surface where the semiconductor layer 4 isformed and the surface of the substrate 11 where the semiconductor layer4 is formed.

When grooves for division are formed on the opposite surface of thesubstrate 11 to the surface where the semiconductor layer 4 is formed,the groove depth is set to extend from the rear surface of the substrate11 to just before the active layer 15. In this embodiment, the groovedepth is set to be somewhat shorter than the thickness of the substrate11 so that a part of the substrate 11 remains. Even when grooves areformed on the surface of the substrate 11 where the semiconductor layer4 is formed, the groove depth for division is preferably set to be20-70% of the thickness of the substrate 11. Additionally, parts of thesemiconductor layer 4, which were damaged through laser-processing,should preferably be removed by dry etching. Chloride or fluoride gasmay be used as etching gas when removing the damaged parts of thesemiconductor layer by dry etching.

FIG. 3 shows a light emitting apparatus comprising the light emittingdevice 1. The light emitting device 1 is inverted so that the substrate11 lies on top and is disposed on a first lead electrode 100. Theelectrode 32 of the device 1 is electrically connected to the first leadelectrode 100 via a conductive material 101. Attention is needed only toadhere the lead electrode 100 immediately onto the conductive material101, and microscopic positioning is not needed. The electrode 31 and then-type contact layer 13 should preferably be coated with an insulativematerial 102 to prevent the conductive material 101 from contactingthem. The insulative material 102 for this coating should preferably bedisposed in the device 1 in advance to cover the exposure region 10. Thepad electrode 34 at the substrate 11 side and a second lead electrode103 are electrically connected through a bonding wire such as a goldwire 104.

When certain voltage or an electric current is supplied to the first andsecond electrodes 100 and 103, an electrical path is formed through thefirst lead electrode 100, the conductive material 101, the electrode 32,the semiconductor layer 4, the electrode 31, the conductive material 3,the electrode 33(34), the bonding wire 104 and the second lead electrode103, so that light can be taken out from the active layer 15. If thelight emitting device 1 is utilized for an LED indicator, the device 1,the electrode 100 and 103 should preferably be molded with resin toimprove the light extraction efficiency.

Since each of the pair of electrodes is disposed respectively on oneside and the other side of the substrate 11, the amount of light shadedby the electrodes can be reduced as compared with a conventional examplewhere both electrodes are disposed on the same side of the substrate,resulting in improvement of the light extraction efficiency.Furthermore, working efficiency in assembling work may also be improvedbecause wire bonding is needed only once. The device can be mountedeasily to a proper position by only aligning the p-type electrodes 32with the base.

Next, a second embodiment will be described by referring to FIGS. 4 and5. FIG. 4 is a bottom plan view of the device 1, which corresponds toFIG. 1. FIG. 5 is a cross sectional view taken along the line V-V ofFIG. 4, which corresponds to FIG. 1. Same reference notes are given tocomponents common with the first embodiment shown in FIGS. 1 and 2, anddescription of them will be omitted to avoid duplication of explanation.Differences will be described mainly.

The device 1 is characterized by comprising a longitudinal hole 20 whichperpendicularly extends to but does not pass through the n-type contactlayer 13. This longitudinal hole 20 is formed in a cylindrical or conedshape of 30 μm-100 μm in diameter by laser beams duringlaser-processing. The longitudinal hole 20 may also be formed in anhourglass shape with diameters of its openings and its bottom wider thanthat in the middle.

In this embodiment, the longitudinal hole 20 of 50 μm in diameter isformed by laser-processing. The longitudinal hole 20 is used as a pathconducting electricity in a perpendicular direction of the device (i.e.an electrical path). To form the electrical path, a conductive material30 such as a metallic thin film is formed to cover the inner surface ofthe longitudinal hole 20. Although the conductive material 30 ispreferably formed by plating, which makes formation of the materialthroughout a microscopic area easier, it may also be formed bydeposition of metal in such cases where the diameter of the hole islarge or a tapered surface is formed. The longitudinal hole 20 may befilled up inside with a conductive material such as metallic materials.

An example of forming the conductive material 30 by plating includesforming a deposited film of 20 nm in thickness on a wall inside thelongitudinal hole 20 prior to plating copper (Cu) by deposition. Thedeposited film is made of titanium (Ti), platinum (Pt), gold (Au) or thelike, each of which can make ohmic contact with the n-type contact layer13. Thus the conductive material 30, or the plated layer is formed onthe wall inside the longitudinal hole 20. The conductive material 30 amay be formed either by exclusively using materials capable of makingohmic contact with the n-type contact layer 11, or by plating orproviding the conductive paste or the like inside the longitudinal hole20 in which a film, which is made of materials capable of making ohmiccontact and which contacts with the n-type contact layer 11, was formed.

The metallic materials to be filled into the longitudinal hole 20 mayinclude conductive paste, molten solder or metallic micro-balls.

In the first embodiment, a part of the n-type contact layer 13 isexposed to form an exposure region by removing a part of thesemiconductor layer 4 laminated thereon. In this embodiment, however,the surface, which makes contact with the semiconductor layer, of thecontact layer 13 is formed in a same planar shape as that of thesemiconductor layer including the p-type contact layer 17 thereon, thusthere is no such exposure region on the contact layer 13.

The longitudinal hole 20 is formed by laser irradiation in the drillingprocess. To reduce the damage to the semiconductor layer 4, it ispreferable to irradiate the laser from the opposite surface (rearsurface) of the substrate 11 to the surface (front surface) where thesemiconductor layer 4 is formed. Although the longitudinal hole 20 isset to be a cylindrical shape with identical diameters from top tobottom, the completed hole 20 is slightly tapered. In this embodiment,for example, the rear surface of the substrate 11 may undergo abacklapping process so that the thickness of the substrate 11 is reducedfrom 350 μm-430 μm to about 45 μm before the laser irradiation. Thelongitudinal hole 20 is formed in a mortar-shape with diameters at theopening and the bottom part respectively 50 μm and 40 μm.

A laser which emits light at a wavelength to be absorbed in thesubstrate 11 is selected, as in the first embodiment. Since thesubstrate 11 is a sapphire substrate, a short-wavelength laser of 500 nmor shorter is used here. In the second embodiment, as in the firstembodiment, an ultra violet laser of wavelength 355 nm which is thethird harmonic of a YAG laser categorized as a solid-state laser isemployed. Other lasers such as YAG laser's fundamental frequency of1,060 nm, second harmonic of 533 nm or fourth harmonic of 266 nm mayalso be employed.

The intensity of the laser beam profile used herein shows a Gaussiandistribution. The longitudinal hole 20 is formed to the extent that itsend reaches the n-type contact layer 13 but not reaches the claddinglayer 14.

As described above, the conductive material 30 connected to the n-typecontact layer 13 comprises a metallic thin film suitable for makingohmic contact with the n-type contact layer 13. An electrode 32 isformed on the p-type contact layer 17 to make ohmic contact therewith.The electrode 32 is formed to cover the entire surface of the p-typecontact layer 17. Alternately, the electrode 32 may be formed to coveronly a part of the p-type contact layer 17. The electrode 32 is areflective electrode to reflect light generated in the device 1.

In such devices where light is taken out from the electrode 32 side, theelectrode 32 may be replaced with a light transmitting electrode thoughwhich light generated in the device 1 can pass. Apart from beingtranslucent, the electrode 32 may be a comb electrode or a meshelectrode made of light-shielding materials, both structured to transmitlight. In the second embodiment, a part of the semiconductor layer 4above the n-type electrode is not removed, which may maintain the broadlight emitting area when light is taken out from the electrode 12 side.

When light is not taken out from the electrode 32 side, lighttransmitted through the electrode 32 may be reflected by a memberdisposed on the opposite side of the electrode 32 to the p-type contactlayer 17. The member reflects the wavelength of light emitted from thedevice.

As shown in FIGS. 4 and 5, an electrode 33a is formed on the oppositesurface of the substrate 11 to the surface where the semiconductor layer4 is formed. The electrode 33 a is electrically connected to theconductive material 30 a disposed inside the longitudinal hole 20. Theconductive material 30 disposed inside the longitudinal hole 20 may alsoserve as the electrode 33 a. The electrode 33 a also serves as a padelectrode 34 a with a predetermined thickness. In the second embodiment,the pad electrode 34 a is disposed to block the opening of thelongitudinal hole 20 to minimize shading areas as shown in FIG. 4. Thepad electrode 34 a may also be disposed apart from the longitudinal hole20 in the same way as shown in FIG. 19, which will be described later.The planar dimension of the pad electrode 34 a is larger than that ofthe opening of the longitudinal hole 20. The pad electrode 34 a is usedfor wire bonding.

As shown in FIG. 4, the pad electrode 34 a and the longitudinal hole 20are disposed at one corner of the substrate 11 in the second embodiment.As shown in FIGS. 6 and 7, however, they may also be disposed near thecenter of one side or at the center of the substrate 11 when viewed as aplane. The longitudinal hole 20 is disposed inside a lateral surface 11a of the substrate 11 at a constant distance from the lateral surface 11a.

As described above, a plurality of devices 1 are formed on a substrateof about two inches in diameter as a wafer (not shown). After that, thewafer is divided into dices to make individual devices. For dividing thewafer, a laser beam used for the formation of the longitudinal hole 20may also be employed to form grooves for division. Grooves for divisionmay be formed on the opposite surface of the substrate 11 to the surfacewhere the semiconductor layer 4 is formed, or on the surface of thesubstrate 11 where the semiconductor layer 4 is formed, or both theopposite surface of the substrate 11 to the surface where thesemiconductor layer 4 is formed and the surface of the substrate 11where the semiconductor layer 4 is formed. When grooves for division areformed on the opposite surface of the substrate 11 to the surface wherethe semiconductor layer 4 is formed, the groove depth is set to extendfrom the rear surface of the substrate 11 to just before the activelayer 15. In this embodiment, the groove depth is set to be somewhatshorter than the thickness of the substrate 11 so that a part of thesubstrate 11 remains. Even when grooves are formed on the surface of thesubstrate 11 where the semiconductor layer 4 is formed, the groove depthfor division is preferably set to be 20-70% of the thickness of thesubstrate 11. Parts of the semiconductor layer 4, which were damagedthrough laser-processing, are removed by dry etching.

In the same manner of forming the grooves for division, deep grooves formaking contact with the n-type contact layer 13 could be formed on therear surface of the substrate 11 in the form of a wafer in thelongitudinal and lateral directions so as to form a grid pattern. Whenthe wafer having such a structure is divided, the division of thedevices may start from the deep grooves, leading a high possibility ofdeformation of the devices.

On the contrary, the longitudinal hole 20 formed in the above-mentionedembodiment is different in shape from the grooves for division. Thedivision of the devices cannot start from the longitudinal hole 20, thuspreventing the deformation upon dividing the devices.

FIG. 8 shows a light emitting apparatus comprising the light emittingdevice 1. The light emitting device 1 is inverted and disposed on afirst lead electrode 100 so that the substrate 11 lies on top for makingthe substrate 11 a light extraction surface. The electrode 32 of thedevice 1 is electrically connected to the first lead electrode 100 via aconductive material 101. The pad electrode 34 a at the substrate 11 sideand a second lead electrode 103 are electrically connected through abonding wire such as a gold wire 104.

When certain voltage or current is supplied to the second leadelectrodes 100 and 103, an electrical path is formed through the firstlead electrode 100, the conductive material 101, the electrode 32, thesemiconductor layer 4, the conductive material 30 a, the electrode 33 a(34 a), the bonding wire 104 and the second lead electrode 103 so thatlight can be taken out from the active layer 15. Therefore, there arefew places in the electrical path wherein electric fields areconcentrated, resulting in a high ESD robustness.

Light which is output from the active layer 15 is taken out of thedevice 1 through the substrate 11. If the light emitting device 1 isutilized for an LED indicator, the device 1, the electrodes 100 and 103should preferably be molded with resin to improve the light extractionefficiency.

Since each one of the pair of electrodes is disposed respectively on oneside and the other side of the substrate 11, light shaded by theelectrodes can be reduced as compared with a conventional example whereboth electrodes are disposed on the same side of the substrate, whichimproves the light extraction efficiency. Furthermore, workingefficiency in assembling work may also be improved because wire bondingis needed only once.

Next, a third embodiment will be described by referring to FIGS. 9 and10. FIG. 9 is a bottom plan view of the device 1, which corresponds toFIG. 4. FIG. 10 is a cross sectional view taken along the line X-X ofFIG. 9, which corresponds to FIG. 5. Same reference notes are given tocomponents which are common with the first embodiment shown in FIGS. 1and 2, and description of them will be omitted to avoid duplication ofexplanation. Differences will be described mainly.

The third embodiment is characterized by adding a groove 35 and aconductive material 36 disposed therein to the second embodiment. Inother words, the groove 35 which does not pass through the semiconductordevice 1 is formed on the rear surface of the substrate 11. The end ofthe groove 35 contacts the n-type contact layer 13.

As the above-mentioned longitudinal hole 20, the groove 35 is formed byirradiating a laser. The groove 35 is joined to the longitudinal hole 20and they are interconnected. The groove 35 is formed inside a lateralsurface 11 a of the substrate 11, at a constant distance from thelateral surface 11 a so that the groove 35 does not protrude beyond thelateral surface 11 a. The groove 35 takes the form of a hollow squarewhen viewed as a plane. The sides of the groove 35 extend along theouter edges of the substrate without intersecting each other so that thesubstrate outside the groove 35 is continuously remained like a frame.Thus an adverse effect caused by the groove 35 in dividing the devicescan be reduced.

A conductive material 36 is formed on surfaces of the groove 35.Although the conductive material 36 is formed from the same material as,and simultaneously with the conductive material 30 used to form theelectrical path in the longitudinal hole 20, it may also be separatelyformed from a material of the same kind. The conductive material 36makes ohmic contact with the n-type contact layer 13 to be electricallyconnected thereto. Therefore, the area in which the n-type contact layer13 and the electrode 33 a are electrically connected is larger than thatof the second embodiment. If the conductive material 36 is formed bymaking a metal capable of making ohmic contact with the n-type contactlayer 13 ultra-thin, the conductive material 36 may be a translucentmaterial which light from the active layer 15 passes through. If theconductive material 30 is formed by making a metal capable of makingohmic contact with the n-type contact layer 13 ultra-thin, theconductive material 30 may be a translucent material which light fromthe active layer 15 passes through. The light extraction efficiency canbe greatly improved, as compared to light shielding types of conductivematerials, if the whole or a part of the conductive material 36 or theconductive material 30 is translucent. This light emitting device isalso utilized in a light emitting apparatus like aforementionedembodiments.

Next, a fourth embodiment will be described by referring to FIGS. 11 and12. FIG. 11 is a bottom plan view of the device 1, which corresponds toFIG. 1. FIG. 12 is a cross sectional view taken along the line X-X ofFIG. 11, which corresponds to FIG. 2. Same reference notes are given tocomponents which are common with the embodiment shown in FIGS. 1 and 2,and description of them will be omitted to avoid duplication ofexplanation. Differences will be described mainly.

The fourth embodiment is characterized by adding a groove 35 and aconductive material 36 disposed therein to the first embodiment. Inother words, the groove 35 which does not pass through the semiconductordevice 1 is formed on the rear surface of the substrate 11. The end ofthe groove 35 contacts the n-type contact layer 13.

As the above-mentioned through hole 2, the groove 35 is formed byirradiating a laser. The groove 35 is joined to the through hole 2 andthey are interconnected. The groove 35 is formed inside a lateralsurface 11 a of the substrate 11 so that the groove 35 does not protrudebeyond the lateral surface 11 a of the substrate 11. A conductivematerial 3 a is formed on the wall inside the through hole 2.

Similar to the third embodiment, the groove 35 takes the form of ahollow square when viewed as a plane. The electrode material 36 made ofthe same or the same kind of a material as the conductive material 3 afor the electrical path formed on the wall inside the through hole 2 isformed inside the groove 35. The electrode material 36 makes ohmiccontact with the n-type contact layer 13 to be electrically connectedthereto. Therefore, the area in which the n-type contact layer 13 andthe electrode 33 are electrically connected is larger than that of thefirst embodiment.

Next, a fifth embodiment will be described by referring to FIGS. 13 and14. FIG. 13 is a bottom plan view of the device 1, which corresponds toFIG. 1. FIG. 14 is a cross sectional view taken along the line X-X ofFIG. 13, which corresponds to FIG. 2. Same reference notes are given tocomponents which are common with the first embodiment shown in FIGS. 1and 2, and description of them will be omitted to avoid duplication ofexplanation. Differences will be described mainly.

The fifth embodiment is characterized by adding longitudinal holes 37,electrode materials 38 disposed therein and an electrode 39 forconnecting the electrode materials 38 at the rear surface of thesubstrate 11 to the first embodiment. In other words, a plurality oflongitudinal holes 37 which do not pass through the semiconductor device1 are formed on the rear surface of the substrate 11. The ends of thelongitudinal holes 37 contact the n-type contact layer 13. As theabove-mentioned through hole 2, the longitudinal holes 37 are formed byirradiating a laser. The longitudinal holes 37 are formed independentlywithout being joined to the through hole 2. The longitudinal holes 37are formed inside a lateral surface 11 a of the substrate 11 so as notto protrude beyond the lateral surface 11 a of the substrate 11. Thelongitudinal holes 37 are formed in the vicinity of three corners of thesubstrate 11, except a corner where the through hole 2 is disposed. Aconductive material 3 b is formed on the wall inside the through hole 2.The electrode materials 38 made of the same or the same kind of amaterial as the conductive material 3 b formed inside the through hole 2is formed on the wall inside the longitudinal holes 37. The conductivematerial 38 makes ohmic contact with the n-type contact layer 13 to beelectrically connected thereto.

The electrode 39 which connects the conductive material 3 b in thethough hole 2 and the electrode materials 38 in the longitudinal holes37 is formed simultaneously with forming the electrode 33. Theconductive material 3 b and the electrode materials 38 areinterconnected on the rear side of the substrate 11 via the electrode39. The electrode materials 38 in the longitudinal holes 37 are alsointerconnected by the material of the electrode 33 which forms the padelectrode 34. Therefore, the area in which the n-type contact layer 13and the electrode 33 are electrically connected is larger than that ofthe first embodiment. Also, the area where the electrode inside thelongitudinal holes 37 shades light can be smaller, as compared to thefourth embodiment.

In each of the above-described embodiments, a pad electrode 40 of acertain thickness may be additionally formed on the electrode 32 asshown in FIG. 14, if the electrode 32 is a thin, light-transmitting typeelectrode, or an electrode is needed for the purpose of wire bonding.

A sixth embodiment illustrated in FIGS. 15 and 16 shows a formation of amesa by means of etching circumferences of the p-type contact layer 17,p-type cladding layer 16, active layer 15 and n-type cladding layer 14to expose the n-type contact layer 13 and a fabrication of an electrodeon the exposed n-type contact layer to electrically connect the n-typecontact layer 13 and the through hole 2. These enable the electriccurrent to be widely distributed through the semiconductor whilepreventing a current concentration on some p-n junction interfaces, thusenhancing ESD robustness.

Next, a seventh embodiment will be described by referring to FIGS. 17and 18. FIG. 17 is a bottom plan view of the device 1, which correspondsto FIG. 4. FIG. 18 is a cross sectional view taken along the line X-X ofFIG. 17, which corresponds to FIG. 5. Same reference notes are given tocomponents which are common with the above-described embodiments, anddescription of them will be omitted to avoid duplication of explanation.Differences will be described mainly.

The seventh embodiment is characterized by adding longitudinal holes 37a, conductive materials 38 a disposed therein and an electrode 39 a forconnecting the conductive materials 38 a at the rear surface of thesubstrate 11 to the second embodiment. A plurality of longitudinal holes37 a which do not pass through the semiconductor device 1 are formed onthe rear surface of the substrate 11. The ends of the longitudinal holes37 a contact the n-type contact layer 13. As the above-mentionedlongitudinal hole 20, the longitudinal holes 37 a are formed byirradiating a laser. The longitudinal holes 37 a are formedindependently without being joined to the longitudinal hole 20. Thelongitudinal holes 37 a are formed inside a lateral surface 11 a of thesubstrate 11 so as not to protrude beyond the lateral surface 11 a ofthe substrate 11. The longitudinal holes 37 are formed in the vicinityof three corners of the substrate 11, except a corner where thelongitudinal hole 20 is disposed. The conductive materials 38 b made ofthe same or the same kind of a material as the conductive material 31 aformed inside the longitudinal hole 20 is formed on the wall inside thelongitudinal holes 37 a. The conductive materials 38 b make ohmiccontact with the n-type contact layer 13 to be electrically connectedthereto.

The electrodes 33 a and 39 a which connect the conductive material 31 ain the longitudinal hole 20 and the conductive materials 38 a in thelongitudinal holes 37 a are formed by simultaneously forming bothmaterials 33 a and 39 a. The conductive material 31 a and the conductivematerials 38 b are interconnected at the rear side of the substrate 11via the electrode 39 a. The electrode material 31 a in the longitudinalhole 20 and the conductive materials 38 b in the longitudinal holes 37 aare interconnected also by a material of the electrode 33 a which formsthe pad electrode 34. If the electrode 39 a is translucent, theelectrode 33 a on the electrode 39 a should preferably be removed exceptfor the pad electrode 34 to prevent the electrode 33 a from shadinglight. Therefore, the area in which the n-type contact layer 13 and theelectrode 33 a are electrically connected is larger than that of thesecond embodiment. Also, the area where the material inside thelongitudinal hole 20 shades light can be smaller, as compared to thethird embodiment. Like aforementioned embodiments, this light emittingdevice is utilized in a light emitting apparatus with an arrangementwhere the substrate 11 lies on top as shown in FIG. 8.

In each of the above-described embodiments, a pad electrode 40 of acertain thickness may be formed additionally on the electrode 32 asshown in FIG. 18, if the electrode 32 is a light-transmitting electrodeor an electrode is needed for the purpose of wire bonding. By doing so,the device of FIG. 18 can be incorporated as it is into thelight-emitting apparatus of FIG. 8, in other words, the surface of thesubstrate 11 on which the semiconductor layer 4 is formed can be used asa light extracting surface. In this case, the electrode 33 on thesubstrate 11 side is connected with the first lead electrode 100, whilethe electrode 40 on the opposite side is connected with the second leadelectrode 103 with wire bonding.

Next, an eighth embodiment will be described by referring to FIGS. 19and. 20. FIG. 19 is a bottom plan view of the device 1, whichcorresponds to FIG. 4. FIG. 20 is a cross sectional view taken along theline X-X of FIG. 19, which corresponds to FIG. 1. Same reference notesare given to components which are common with the above-describedembodiments and description of them will be omitted to avoid duplicationof explanation. Differences will be described mainly.

The eighth embodiment is characterized by that the cross sectional shapeof the longitudinal hole 20 of the second embodiment is tapered towardthe depth direction and that the pad electrode 34 b connected to theconductive material 31 a is disposed separately from the longitudinalhole 20 a. In other words, the shape of the longitudinal hole 20 a ischanged from a cylindrical shape to a truncated cone shape. Such alongitudinal hole 20 a may be formed by laser-processing, for example,using a laser having intensity distribution in which intensity peaks ofthe laser with a Gaussian beam profile are truncated (beam profile of ashaped beam).

Since the longitudinal hole 20 a is shaped as described above, theconductive material 30 a can be easily formed to a predeterminedthickness on a wall inside the hole 20 a from the rear side of thesubstrate 11 by deposition, sputtering and so on. Also, the slantedsurface of the longitudinal hole 20 a can be utilized as a lightreflecting surface. Like aforementioned embodiments, this light emittingdevice is also utilized in a light emitting apparatus with anarrangement where the substrate 11 lies on top as shown in FIG. 21.

Although the longitudinal hole 20 a is disposed at the center of thesubstrate and the pad electrode 34 b is disposed adjacently to thecenter of a side next to electrode 34 b, the disposition may be changedas shown in FIG. 22. FIG. 22(a) shows an example where the longitudinalhole 20 a is disposed at the center of the substrate while the padelectrode 34 a is disposed at a corner of the substrate 11. FIG. 22(b)shows an example where the longitudinal hole 20 a is disposed at onecorner on one diagonal line of the substrate 11 while the pad electrode34 b is disposed at the other corner on the diagonal line of thesubstrate 11. FIG. 22(c) shows an example where the longitudinal hole 20a is disposed adjacently to the center part of a side of the substrate11 while the pad electrode 34 b is disposed at a corner of the substrate11. FIG. 22(d) shows an example where the longitudinal holes 20 a aredisposed at both corners on one diagonal line of the substrate 11 whilethe pad electrode 34 b is disposed at a corner on the other diagonalline of the substrate 34 a.

Like aforementioned embodiments, this light emitting device is alsoutilized in a light emitting apparatus with an arrangement where thesubstrate 11 lies on top as shown in FIG. 21.

The present invention is not limited to the embodiments described above,but can be modified in various ways without departing from subjectmatters of the invention. For example, the invention may be applicableto a device utilizing a semiconductor substrate other than an insulativesubstrate as the substrate 11.

As described above, the present invention realizes a high-efficiencylight extraction. Also the present invention can enhance ESD robustnessof a device.

The device can be mounted easily to a proper position by only aligningthe second conductivity type semiconductor layer with the base.

Industrial Applicability

As described above, the compound semiconductor light emitting device ofthe present invention is suitable for a blue light emitting diode, ablue laser diode and the like.

1. A compound semiconductor light emitting device comprising: aninsulative substrate; a semiconductor layer including a plurality ofsemiconductor thin film layers laminated on one surface of theinsulative substrate to form an active layer; one electrode provided ontop surface of the semiconductor layer; the other electrode provided onthe other surface of the insulative substrate; an exposure region formedby removing semiconductor on a semiconductor thin film layer so that thefirst semiconductor thin film layer to be connected to the otherelectrode is exposed; a through hole penetrating the insulativesubstrate and the first semiconductor thin film layer in the exposureregion; an electrical path formed in the through hole to electricallyconnect the first semiconductor thin film layer and the other electrode;and an ohmic electrode which is electrically connected to the electricalpath formed in the through hole and which makes ohmic contact to thefirst semiconductor thin film layer located in the exposure region. 2.The compound semiconductor light emitting device according to claim 1,wherein the electrical path is comprised of either a conductive materialformed on a wall inside the through hole or a conductive material filledin the through hole.
 3. (Canceled)
 4. The compound semiconductor lightemitting device according to claim 1, wherein the insulative substrateis a sapphire substrate, and the semiconductor thin film layer is agallium nitride compound semiconductor layer.
 5. (Canceled)
 6. Thecompound semiconductor light emitting device according to claim 1,wherein a diameter of the through hole ranges from 30 μm to 100 μm. 7.The compound semiconductor light emitting device according to any one ofclaims 1, 4 or 6, wherein a groove or a longitudinal hole in addition tothe through hole is formed in the insulative substrate so that theelectrode provided on the other surface of the insulative substrate andthe first semiconductor thin film layer are electrically connectedthrough an electrical path in addition to the electrical path.
 8. Amanufacturing method of a compound semiconductor light emitting devicecomprising: laminating a semiconductor layer including a plurality ofsemiconductor thin film layers on one surface of an insulative substrateto form an active layer; and providing one electrode on top surface ofthe semiconductor layer and the method further comprising: forming anexposure region by removing semiconductor films on first semiconductorthin film layer so that the first semiconductor thin film layer to becontacted with the other electrode is exposed; forming a through holepenetrating the insulative substrate and the first semiconductor thinfilm layer by laser processing in the exposure region; forming anelectrical path in the through hole; forming an ohmic electrode which iselectrically connected to the electrical path and which makes ohmiccontact to the first semiconductor thin film layer located in theexposure region; and electrically connecting an electrode provided onthe other surface of the insulative substrate and the firstsemiconductor thin film layer through the electrical path formed in thethrough hole and the ohmic contact.
 9. The manufacturing method of thecompound semiconductor light emitting device according to claim 8,wherein the through hole penetrating the device is formed in theexposure region by irradiating a laser from the laminated semiconductorlayer.
 10. The method of the compound semiconductor light emittingdevice according to claim 7, wherein an inside of the through hole iscleaned by dry etching after the through hole is formed.
 11. The methodof the compound semiconductor light emitting device according to claim8, wherein an inside of the through hole is cleaned by dry etching usingchloride or fluoride gas after the through hole is formed.
 12. Themanufacturing method of a compound semiconductor light emitting deviceaccording to claim 8, wherein a wafer including a plurality of the lightemitting devices is divided into individual light emitting devices alonggrooves formed by laser-processing.
 13. The method of the compoundsemiconductor light emitting device according to claim 12, whereinsemiconductor layers damaged by laser-processing are removed by dryetching using chloride or fluoride gas after the grooves are formed. 14.The method of the compound semiconductor light emitting device accordingto claim 12, wherein laser-processing for forming the grooves isperformed from the insulative substrate side, or from the laminatedsemiconductor layer side, or from both the insulative substrate side andthe laminated semiconductor layer side.
 15. A compound semiconductorlight emitting device comprising: an insulative substrate which is asapphire substrate; a first conductivity type semiconductor thin filmlayer formed on one surface of the insulative substrate; an active layerformed on the first conductivity type semiconductor thin film layer; asecond conductivity type semiconductor thin film layer formed on theactive layer; one electrode provided on the second conductivity typesemiconductor thin film layer; the other electrode provided on the othersurface of the insulative substrate; a longitudinal hole formed bylaser-processing so as to penetrate the insulative substrate and have adepth reaching the first conductivity type semiconductor thin film layerto be connected to the other electrode; an electrical path made of aconductive material formed in the longitudinal hole to electricallyconnect the first semiconductor thin film layer and the other electrode;a base which comprises a first lead electrode; a second lead electrode;wherein the one electrode is connected to the first lead electrode onthe base; the other electrode is connected to the second lead electrodethrough a bonding wire; and light is extracted mainly from theinsulative substrate side.
 16. The compound semiconductor light emittingdevice according to claim 15, wherein the conductive material is whollyor partially translucent.
 17. The compound semiconductor light emittingdevice according to claim 15, wherein the longitudinal hole is coveredwith a pad electrode with a larger diameter than a diameter of thelongitudinal hole.
 18. The compound semiconductor light emitting deviceaccording to any one of claims 15 to 17, wherein the longitudinal holeis formed inside a lateral surface of the substrate at a constantdistance from the lateral surface.
 19. The compound semiconductor lightemitting device according to claim 15, wherein a pad electrode isdisposed apart from the longitudinal hole on the other surface of theinsulative substrate; and the pad electrode and the conductive materialare electrically connected.
 20. The compound semiconductor lightemitting device according to any one of claims 15 to 17, wherein adiameter of the longitudinal hole ranges from 30 μm to 100 μm.
 21. Thecompound semiconductor light emitting device according to any one ofclaims 15 to 17, wherein a cross sectional shape of the longitudinalhole is tapered toward a depth direction.
 22. The compound semiconductorlight emitting device according to any one of claims 15 to 17, whereinthe semiconductor thin film layer is a gallium nitride compoundsemiconductor layer.
 23. (Canceled)
 24. The compound semiconductor lightemitting device according to claim 15, wherein a plurality of thelongitudinal holes are formed; and conductive materials disposed in theplurality of the longitudinal holes are interconnected on the othersurface of the insulative substrate.
 25. The compound semiconductorlight emitting device according to claim 15, wherein the longitudinalhole is formed by irradiating a laser from the insulative substrateside.
 26. The compound semiconductor light emitting device according toclaim 15, wherein an inside of the longitudinal hole is cleaned by dryetching using chloride or fluoride gas after the longitudinal hole isformed.
 27. A manufacturing method of a compound semiconductor lightemitting device comprising: laminating a first conductivity typesemiconductor thin film layer, an active layer, and a secondconductivity type semiconductor thin film layer on one surface of aninsulative substrate; and providing one electrode and the otherelectrode respectively on top surface of the second conductivity typesemiconductor thin film layer and on the other surface of the insulativesubstrate, and the method further comprising: forming a longitudinalhole by irradiating a short-wavelength laser of 500 nm or shorter so asto have a depth reaching from the other surface of the insulativesubstrate to the first conductivity type semiconductor thin film layerto be connected to the other electrode; electrically connecting theelectrode provided on the other surface of the insulative substrate andthe first semiconductor thin film layer through a conductive materialformed in the longitudinal hole; connecting the one electrode and afirst lead electrode on a base; and connecting the other electrode and asecond lead electrode through a bonding wire.
 28. The manufacturingmethod of a compound semiconductor light emitting device according toclaim 27, wherein a wafer including a plurality of the light emittingdevices is divided into individual light emitting devices along groovesformed by laser-processing.
 29. The manufacturing method of a compoundsemiconductor light emitting device according to claim 28, whereinsemiconductor layers damaged by laser-processing are removed by dryetching using chloride or fluoride gas after the grooves are formed. 30.The manufacturing method of a compound semiconductor light emittingdevice according to claim 29, wherein laser-processing for forming thegrooves are performed from the insulative substrate side, or from thelaminated semiconductor layer side, or from both the insulativesubstrate side and the laminated semiconductor layer side. 31.(Canceled)
 32. The compound semiconductor light emitting deviceaccording to claim 1, wherein an insulative material is provided tocover the exposure region including the ohmic electrode.
 33. Thecompound semiconductor light emitting device according to claim 1,wherein the other electrode for the electrical path provided on theother surface of the insulative substrate comprises a pad electrode forwire bonding.
 34. The compound semiconductor light emitting deviceaccording to claim 4 comprising a base which comprises a first leadelectrode, and a second lead electrode; wherein the one electrode isconnected to the first lead electrode on the base; the other electrodeis connected to the second lead electrode through a bonding wire; andlight is extracted mainly from the insulative substrate side.
 35. Themanufacturing method of a compound semiconductor light emitting deviceaccording to claim 8, wherein the ohmic electrode is connected to thefirst lead electrode on the base; the other electrode is connected tothe second lead electrode through a bonding wire; and light is extractedmainly from the insulative substrate side.